The present invention relates to material deposition; and more particularly, to a planetary type multi-substrate holder system for pulse laser deposition.
Particularly, the present invention relates to a gearless substrate holder capable of withstanding high temperatures, common for material deposition processes, and free of failures associated with mechanical malfunctions of geared substrate holders.
Additionally, the present invention relates to a multi-substrate holder having a plurality of circularly shaped openings in each of which an individual substrate is held and self-rotated once the multi-substrate holder is driven to rotate in either the vertical or horizontal plane. When the multi-substrate holder is rotated vertically, each substrate is self-rotated by gravity assist. When the multi-substrate holder is rotated in horizontal plane, each substrate is self-rotated due to centrifugal forces applied thereto and created by rotation of the multi-substrate holder.
Typically, conventional planetary substrate holders employ mechanical gears to which substrates are attached and by which the substrates are rotated for material deposition thereon. The mechanical gears constitute a xe2x80x9cbottleneckxe2x80x9d area of the material deposition systems since they often develop mechanical malfunctions as a result of continuous use. Additionally, they are vulnerable to high temperature processes typical in material deposition processes. In addition to a limited lifetime and problems associated with high temperature applications, the conventional geared substrate holders have relatively high inventory cost since an individual mechanical gear is needed for each substrate holder.
It is therefore highly desirable in the material deposition art, especially for pulse laser deposition, to provide a multi-substrate holder which does not need a gear for each substrate rotation.
It is therefore an object of the present invention to provide a planetary gearless multi-substrate holder with an extended lifetime which easily withstands high temperature applications and results in lowering the final product cost due to the increase of production speed of a material deposition process.
It is another object of the present invention to provide a gearless substrate holder having a plurality of circumferentially shaped openings of a predetermined diameter in each of which a substrate of circular shape is maintained and self-rotates due either to gravitational or centrifugal forces applied to the substrates when the substrate holder is driven to rotate either in the vertical or horizontal planes, respectively.
It is a further object of the present invention to provide a method for material deposition by using a multi-substrate holder with a plurality of openings defined therein in each of which a substrate self-rotates without a mechanical gear and relies on gravity assist or centrifugal force applied to the substrates when the multi-substrate holder is rotated.
Although the present invention may find its utility in a variety of systems for material deposition, the specific usefulness of the present invention is foreseen in the area of pulse laser deposition. In accordance with the teachings of the present invention, a planetary multi-substrate holder system includes a substrate holder having a plurality of circumferentially shaped openings of a first diameter, a mechanism for rotating the substrate holder about the center of rotation thereof, and an annularly shaped element attached to the sample holder at each of the openings and extending along the peripheral thereof. Preferably, the openings defined within the substrate holder are equidistantly spaced along the circumference of the substrate holder.
Circularly shaped substrates of a diameter smaller than the diameter of each opening are positioned within the openings and held therein by the annularly shaped elements with a portion of the contour of each substrate in contiguous contact with a respective portion of the contour of an opening. Such contiguous contact between the contours of the substrate and the opening is maintained either by gravitational force applied to the substrate, when the substrate holder rotates in the vertical plane; or by centrifugal force applied to the substrate from the center of rotation of the substrate holder when the latter rotates in the horizontal plane.
It is of importance that there is a ledge extending in coinciding relationship with the contour of each opening in order that the respective portion of the contour of each substrate leans or abuts against the ledge when the substrate holder rotates. When the substrate holder rotates in vertical direction, a portion of the contour of each substrate presses against the lowermost portion of the contour of the opening. When the substrate holder rotates horizontally, the substrates press against the portion of the contour of the openings the most distant from the center of rotation of the substrate holder.
Each annularly shaped element can be attached to the substrate holder either by fasteners, or, when the annularly shaped elements are made of ferromagnetic metal, they can be secured against the substrate holder by means of a magnet unit positioned at a side of the substrate holder opposite to the annularly shaped elements thus holding the same attached to the substrate holder.
Viewing another aspect of the present invention, there is provided a method for material deposition which comprises the following steps:
positioning a substrate holder at a predetermined location relative to a target containing at least one deposition material where the substrate holder has a plurality of substantially circularly shaped openings of a predetermined diameter,
securing substrates in respective openings where each substrate is substantially circularly shaped substrate having a diameter smaller than the diameter of the openings,
rotating the substrate holder in either a vertical or horizontal plane to cause self-rotation of each substrate within its respective opening due to the gravitational force applied to each substrate (when the substrate holder is vertically rotated) or due to centrifugal force caused by rotation of the substrate holder in horizontal plane, and
directing an energetic beam towards the target to ablate the deposition material(s) therefrom to deposit the same on the self-rotating substrates. It is essential that no scanning of the energetic beam over the surface of the target is needed for the material deposition technique of the present invention and for obtaining high-quality films on the substrates.
These and other novel features and advantages of the subject invention will be more fully understood from the following detailed description of the accompanying drawings.